GOST 11739.11-98

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  ГОСТ 11739.11-98

GOST 11739.11−98 Alloys, aluminum casting and wrought. Methods for determination of magnesium

GOST 11739.11−98

Group B59

INTERSTATE STANDARD

ALLOYS ALUMINIUM CAST AND WROUGHT

Methods for determination of magnesium

Aluminium casting and wrought alloys.
Methods for determination of magnesium

ISS 77.120.10
AXTU 1709

Date of implementation 2000−01−01

Preface

1 DEVELOPED by JSC «Russian Institute of light alloys» (JSC VILS), the Interstate technical Committee for standardization MTK 297 «Materials and semi-finished products of light alloys"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol of 12 November 1998 No. 14−98)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology, dated April 21, 1999 No. 132 inter-state standard GOST 11739.11−98 introduced directly as state standard of the Russian Federation from January 1, 2000

4 REPLACE GOST 11739.11−82

1 Scope

This standard establishes titrimetric (mass fraction in range from 0.1 to 13.0%) and atomic absorption (at a mass fraction of from 0.01 to 13.0%) methods for determination of magnesium.

2 Normative references

The present standard features references to the following standards:

GOST 61−75 acetic Acid. Specifications

GOST 804−93 primary Magnesium ingots. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 3773−72 Ammonium chloride. Specifications

GOST 4038−79 Nickel (II) chloride 6-water. Specifications

GOST 4140−74 Strontium chloride 6-water. Specifications

GOST 4147−74 Iron (III) chloride 6-water. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4233−77 Sodium chloride. Specifications

GOST 4328−77 Sodium hydroxide. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5456−79 of Hydroxylamine hydrochloride. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 8864−71 Sodium diethyldithiocarbamate 3-water. Specifications

GOST 10484−78 hydrofluoric Acid. Specifications

GOST 10652−73 Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B)

GOST 10929−76 Hydrogen peroxide. Specifications

GOST 11069−74* Aluminium primary. Brand

_______________
* Canceled. Valid GOST 11069−2001. — Note the CODE.

GOST 18300−87 ethyl rectified technical

GOST 25086−87 non-ferrous metals and their alloys. General requirements for methods of analysis

3 General requirements

3.1 General requirements for methods of analysis GOST 25086 with the Supplement.

3.1.1 the result of the analysis be the arithmetic mean of results of two parallel measurements.

4 Titrimetric method for the determination of magnesium

4.1 the essence of the method

The method is based on dissolving the sample in sodium hydroxide solution or hydrochloric acid solution, separation of magnesium from interfering components sodium hydroxide and sodium diethyldithiocarbamate, the titration of magnesium with a solution of Trilon B with eriochrome black T as indicator.

4.2 Equipment, reagents and solutions

Drying oven with thermostat.

a pH meter.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cm, mortar 1:1 and 1:99.

Nitric acid according to GOST 4461 density of 1,35−1,40 g/cmand a solution of 2:3.

Sulfuric acid according to GOST 4204 density 1.84 g/cm, a solution of 1:3.

Hydrofluoric acid according to GOST 10484.

Acetic acid according to GOST 61 density of 1.05 g/cm, a solution of 1:1.

Sodium hydroxide according to GOST 4328, solutions of 200 g/land 2 g/DM.

Hydrogen peroxide according to GOST 10929.

Iron (III) chloride 6-water according to GOST 4147, a solution of 3 g/DM: 0.5 g of iron (III) chloride is placed in a conical flask with a capacity of 100 cmand dissolved in 5 cmof hydrochloric acid of 1:1 and 10 cmwater. The solution was transferred to volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Sodium chloride according to GOST 4233, solution 100 g/DM.

Ammonium chloride according to GOST 3773, solution 100 g/DM.

Ammonia water according to GOST 3760.

Buffer solution pH 10: 70 g ammonium chloride was placed in a volumetric flask capacity 1000 cmand dissolved in 200 cmof water, pour the 570 cmof ammonia, made up to the mark with water mix. The solution was stored in a plastic container.

The technical rectified ethyl alcohol according to GOST 18300.

Sodium diethyldithiocarbamate according to GOST 8864, a solution of 50 g/DM.

Eriochrome black T: 0.1 g of eriochrome black T was mixed with 10 g of sodium chloride and triturated in a porcelain mortar until a homogeneous mixture. Allowed the use of the indicator in solution: 0.125 g of eriochrome black T dissolved in 5 cmof buffer solution with pH 10 and a flow of 50 cmof ethanol. The solution is ready for use within two weeks.

Universal indicator paper.

The indicator Congo red: 0.1 g of the reagent dissolved in 100 cmof water at weak heating, the solution was cooled and stirred.

Indicator paper Congo: medium-density filters («white ribbon») is impregnated with a solution of Congo red, dried in a drying Cabinet at a temperature of 100−105 °C, sliced and stored in boxe. The paper is suitable for use within one month.

Adsorbent (materiana paper): 100 g of crushed filters (red ribbon) is placed in a beaker with a capacity of 500 cm, 300 cm pouredhot water and stirred with a stirrer to obtain a homogeneous mass.

Magnesium GOST-804 brand Mg95.

Standard solutions of magnesium.

Solution a: 1 g of magnesium was placed in a conical flask with a capacity of 500 cm, 200 cm pouredwater and gently portions 30 cmof a hydrochloric acid solution 1:1. After dissolution, the solution was cooled, transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of magnesium.

Solution B: 100 cmsolution And transferred to a volumetric flask with a capacity of 500 cm, pour 6 cmof a hydrochloric acid solution 1:1, made up to the mark with water and mix.

1 cmof a solution contains 0.0002 g of magnesium.

Hydroxylamine hydrochloride according to GOST 5456.

Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652, a solution of molar concentration 0.05 mol/DM: 18,62 g Trilon B, is placed in a beaker with a capacity of 800 cm, dissolved in 500 cmof a solution of sodium hydroxide 2 g/DM, acidified with acetic acid to pH 6 by universal indicator paper. The solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

To establish the mass concentration of the solution Trilon B molar concentration of 0.05 mol/DMfor magnesium in three conical flasks with a capacity of 250 cmeach are placed 15 cmstandard solution And poured in 100 cmof solution in the reference experiment, 10 cmof a solution of ammonium chloride, a pH of 8−9 sets on the universal indicator paper by adding ammonia. The solutions were heated to a temperature of 40−60 °C, poured on a 10 cmbuffer solution, add 0.1 g of indicator mixture or 6−8 drops of the indicator solution eriochrome black T and titrate with a solution of Trilon B to switch crimson colouring solutions in blue.

Trilon B solution molar concentration of 0.02 mol/DM, prepare one of the following ways.

Of 7.45 g Trilon B was placed in a beaker with a capacity of 800 cm, dissolved in 500 cmof a solution of sodium hydroxide 2 g/DM, acidified with acetic acid to pH 6 by universal indicator paper. The solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. Allowed another way: 200 cmof the solution Trilon B molar concentration of 0.05 mol/DMtransferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

To establish the mass concentration of the solution Trilon B molar concentration of 0.02 mol/DMfor magnesium in three conical flasks with a capacity of 250 cmeach are placed 10 cmstandard solution B, and poured in 100 cmof solution in the reference experiment, 10 cmof a solution of ammonium chloride and then do as described above (determination of the mass concentration of the solution Trilon B molar concentration of 0.05 mol/DM).

The mass concentration of the solution Trilon B by magnesium T, g/cm, determined with each batch of samples and is calculated by the formula

, (1)

where mass concentration of a standard solution of magnesium, g/cm;

 — the volume of a standard solution of magnesium, used for titration, cm;

 — volume of solution Trilon B, spent on titration, sm.

4.3 analysis

4.3.1 When the mass fraction of silicon is less than 3%

A portion of the sample weight in accordance with table 1 were placed in a glass with a capacity of 400 cm, flow of 5−10 cmof water and carefully poured in small portions to 30 cmof sodium hydroxide solution 200 g/l(calculated on 6 g of sodium hydroxide per 1 g of sample weight of sample).


Table 1

After the cessation of violent reaction solution is heated to dissolve the sample, pour 2−3 cmof hydrogen peroxide and boil for 2−3 minutes, the solution was poured 200 cmof hot water, 5 cmof a solution of ferric chloride (III), if the mass fraction of iron in the alloy is less than 0.5%, stirred and allowed to settle sediment for 20−30 min.

4.3.2 When the mass fraction of silicon of more than 3%

A portion of the sample weight in accordance with table 1 was placed in a conical flask with a capacity of 400 cm, flow of 5−10 cmof water and carefully, in small portions pour 50 cmof a hydrochloric acid solution 1:1. After the cessation of violent reaction solution is heated to dissolve the sample, pour 10 cmof nitric acid solution, heated, without boiling, until the termination of allocation of brown fumes of oxides of nitrogen, and then gently boiled for 10 min. Pour hot water up to 150 cmand, if the solution is opaque or in the presence of sediment, filtered through a filter medium density («white ribbon») with an adsorbent in a conical flask with a capacity of 500 cm(stock solution). The filter is then washed 8−10 times with hot hydrochloric acid 1:99 in portions of 10−15 cm, collecting the washings in the same flask.

The filter with precipitate was placed in a platinum crucible, dried, incinerated, preventing ignition, and calcined at 500−600 °C for 2−3 min. After cooling in the crucible add ten drops of sulfuric acid, 10 cmhydrofluoric acid and drop by drop nitric acid (approximately 1 cm) to obtain a transparent solution. The solution was evaporated to dryness, poured to the dry residue of 10 cmsolution of hydrochloric acid 1:1 and dissolved under moderate heating. After cooling, the solution is attached to the main solution in the flask (if necessary, filtered).

Into the solution pour 5 cmof a solution of ferric chloride (III), if the mass fraction of iron in the alloy is less than 0.5%, and put it under continuous stirring in a beaker with a capacity of 600 cm, containing sodium hydroxide solution 200 g/DMin accordance with table 1. Into the solution pour 2−3 cmof hydrogen peroxide, boil for 10 minutes and give the residue to soak for 20

-30 min.

4.3.3 Sediment obtained in 4.3.1 and 4.3.2, filtered through the filter medium density («white ribbon»), washed 4−5 times with hot sodium hydroxide solution 2 g/DMand twice with water.

The bulk of the sediment washed from the filter with a jet of hot water into the flask, which held a dissolution and the remaining precipitate on the filter is dissolved in 30 cmof warm hydrochloric acid solution 1:1 and 3 cmof hydrogen peroxide. The filter is washed with hot water (until the red color of Congo paper, is placed on the edge of the filter), collecting the washings in the same flask. The resulting solution was heated to boiling and boil at low heating for 5 min, the solution volume should be about 100 cm. The solution is placed in the paper of the Congo, pour 15 cmof a solution of ammonium chloride, cooled and set to pH 3 with sodium hydroxide solution 200 g/DM(blue-purple coloration of the paper of the Congo from a single drop of sodium hydroxide solution), additionally controlling universal indicator paper. The cooled solution was transferred to volumetric flask with a capacity of 250 cm, 80 cm pour thesolution diethyldithiocarbamate sodium, made up to the mark with water and stirred, while the pH value is 4.5−5. The solution is filtered through a dry filter medium density (white ribbon) in a dry beaker, rejecting the first portions of the filtrate. For the mass concentration of manganese greater than 0.5%, the solution was filtered through two dense dry filter (the"blue ribbon»).

At temperatures below 20 °C may appear whitish turbidity of diethyldithiocarbamate sodium, which further titration is not crimp terminals and wiring harnesses

T.

4.3.4 Aliquot part of the solution in accordance with table 1 was placed in a conical flask with a capacity of 500−250 cm, top up with water to 150 cmand is heated to a temperature of 40−60 °C. To the solution was added a few crystals of hydroxylamine hydrochloride, 10 cmbuffer solution and 0.1 g of indicator mixture or 6−8 drops of the indicator solution. The solution temperature of 40−60 °C and titrated in accordance with table 1 with a solution of Trilon B of 0.05 or 0.02 mol/DMof transition to the crimson color of the solution blue.

4.3.5 Solution of the reference experiment are prepared according to 4.3.1−4.3.4 with all the reagents used in the analysis.

4.4 Processing of results

4.4.1 Mass fraction of magnesium in % is calculated by the formula

, (2)

where  — volume of solution Trilon B, used for titration of the sample solution, cm;

 — volume of solution Trilon B, used for titration of the solution in the reference experiment, cm;

 — established mass concentration of the solution Trilon B on the magnesium, g/cm;

 — the weight of the portion of the sample in aliquote part of the solution, g

.

4.4.2 discrepancies in the results must not exceed the values given in table 2.

Table 2

Percentage

5 Atomic absorption method for determination of magnesium

5.1 the essence of the method

The method is based on dissolving the samples in hydrochloric acid in the presence of hydrogen peroxide and measuring the atomic absorption of magnesium at a wavelength of RUB 285.2 nm or less sensitive — 279,6 nm in the flame acetylene-air in the presence of chloride or strontium in the flame acetylene-nitrous oxide.

5.2 the Instrument, reagents and solutions

Spectrophotometer of atomic absorption with a radiation source for magnesium.

Acetylene according to GOST 5457.

Nitrous oxide medical.

Hydrochloric acid according to GOST 3118 density of 1.19 g/cm, mortar 1:1 and 1:99.

Sulfuric acid according to GOST 4204 density 1.84 g/cm.

Nitric acid according to GOST 4461 density of 1,35−1,40 g/cm.

Hydrofluoric acid according to GOST 10484.

Nickel (II) chloride 6-water according to GOST 4038, a solution of 2 g/DM.

Hydrogen peroxide according to GOST 10929.

Strontium chloride 6-water according to GOST 4140, a solution of 50 g/DM:

76 g of strontium chloride were placed in a glass with a capacity of 600 cm, is dissolved in 400 cmof water, transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. Store in a plastic container.

Aluminium GOST 11069 brand А999.

Solutions of aluminum.

Solution a 20 g/l: 10 g of aluminum is placed in a conical flask with a capacity of 500 cm, poured in small portions 400 cmof a hydrochloric acid solution of 1:1 and dissolved at a moderate heat, adding 1 cmof a solution of Nickel chloride (II).

Then add 3−5 drops of hydrogen peroxide and boil the solution for 3−5 min. the Cooled solution was transferred to a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

Solution B 1 g/l: 50 cmsolution And placed in a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

Magnesium GOST-804 brand Mg95.

Standard solutions of magnesium.

Solution a: 1 g of magnesium was placed in a conical flask with a capacity of 250 cm, 100 cm pour thewater, carefully, in small portions 30 cmof a hydrochloric acid solution of 1:1 and dissolved under moderate heating. The cooled solution is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 g of magnesium.

Solution B: 5 cmmortar And transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution is prepared immediately before use.

1 cmof the solution contains

Of 0.00005 g of magnesium.

5.3 analysis

5.3.1 Sample the sample weight of 0.5 g was placed in a conical flask with a capacity of 250 cm, 30 cm, pour thewater cautiously, in small portions of 20 cmof a hydrochloric acid solution 1:1. The flask is heated to dissolve the sample, add 3−5 drops of hydrogen peroxide and boil the solution for 3−5 min. If the solution is clear, he was transferred to volumetric flasks according to table 3.


Table 3

5.3.2 If residue remains, indicating the presence of silicon, the solution was filtered into a measuring flask in accordance with table 3 through the filter medium density («white ribbon»), washing the precipitate on the filter 2−3 times with hot hydrochloric acid 1:99 in portions of 10 cm(core solution).

The filter with precipitate was placed in a platinum crucible, dried, incinerated, preventing ignition, and calcined at 500−600 °C for 2−3 min. After cooling in the crucible add five drops of sulfuric acid, 5 cmhydrofluoric acid and drop by drop nitric acid (approximately 1 cm) to obtain a transparent solution. The solution was evaporated to dryness, cooled, poured to the dry residue in the crucible 10 cmof hydrochloric acid 1:1 and dissolved under moderate heating. After cooling, the solution is attached to the main solution (if necessary, previously filtered).

5.3.3 When the mass fraction of magnesium is less than 0.05%

To the solution in a volumetric flask with a capacity of 250 cm, obtained by 5.3.1 and 5.3.2, poured 20 cmof a solution of chloride of strontium (using the flame of acetylene-air), made up to the mark with water and mix.

5.3.4 for the mass concentration of magnesium, more than 0.05%

Solutions in a volumetric flask with a capacity of 500 cm, but received 5.3.1 and 5.3.2, made up to the mark with water and mix.

5.3.5 When the mass fraction of magnesium of from 0.5 to 13.0%

Aliquot part 200 cmof the solution obtained in 5.3.4, is placed in a volumetric flask with a capacity of 500 cm, made up to the mark with water and mix.

5.3.6 Aliquot part of the solution obtained in 5.3.4 and 5.3.5, in accordance with table 3 is placed in a volumetric flask with a capacity of 250 cm, 5 cm pour thesolution of chloride of strontium (using the flame of acetylene-air), made up to the mark with water and mix.

5.3.7 Solution in the reference experiment are prepared according to 5.3.1 to 5.3.6 using is sample the sample the sample of aluminium.

5.3.8 Construction of calibration graphs

5.3.8.1 If the mass fraction of magnesium from 0.01 to 0.05%

In seven volumetric flasks with a capacity of 250 cmeach poured in 25 cmof a solution of aluminum And at 20 cmof a solution of chloride of strontium (using the flame of acetylene-air), in six of them measure 0,5; 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,000025; 0,00005; 0,0001; 0,00015; 0,0002; 0,00025 g of magnesium.

5.3.8.2 for the mass concentration of magnesium, more than 0.05 to 0.25 percent

In six volumetric flasks with a capacity of 250 cmeach poured in 5 cmof a solution of aluminum And at 5 cmof strontium chloride solution (when using the flame of acetylene-air), five of them measure 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,00005; 0,0001; 0,00015; 0,0002; 0.00025 grams of magnesium.

5.3.8.3 for the mass concentration of magnesium in excess of 0.25 to 1.0%

In six volumetric flasks with a capacity of 250 cmeach poured in 25 cmof a solution of aluminium B 5 cmof strontium chloride solution (when using the flame of acetylene-air), five of them measure 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,00005; 0,0001; 0,00015; 0,0002; 0.00025 grams of magnesium.

5.3.8.4 for the mass concentration of magnesium in excess of 1.0 to 13.0

In six volumetric flasks with a capacity of 250 cmeach poured in 5 cmof a solution of aluminium B 5 cmof strontium chloride solution (when using the flame of acetylene-air), five of them measure 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,00005; 0,0001, 0,00015; 0,0002; 0.00025 grams of magnesium.

5.3.8.5 Solutions for 5.3.8.1−5.3.8.4 topped up to the mark with water and mix.

5.3.9 Solutions of the samples in the reference experiment and the solutions for constructing the calibration curve is sprayed into the flame of acetylene-air or acetylene-nitrous oxide and measured by atomic absorption at a wavelength of 279,6 or RUB 285.2 mm.

According to the obtained values of atomic absorption and corresponding mass concentrations of magnesium to build a calibration curve in the coordinates: «the Value of atomic absorption — mass concentration of magnesium, g/cm». A solution in which magnesium has not been introduced, serves as a solution control experience in construction of calibration curve.

Mass concentration of magnesium in the sample solution and the solution of control and experience determined by the calibration schedule.

5.4 processing of the results

5.4.1 Mass fraction of magnesium in % is calculated by the formula

, (3)

where is the mass concentration of magnesium in the sample solution found by the calibration schedule, g/cm;

mass concentration of magnesium in solution in the reference experiment, was found in the calibration schedule, g/cm;

 — the volume of the sample solution, cm;

 — the weight of the portion of the sample or the weight of the portion of the sample in aliquote part of the solution, g

.

5.4.2 the Divergence of results should not exceed the values given in table 4.


Table 4

Percentage